This study will evaluate the hypocholesterolemic effects and influence on cholesterol biosynthesis of the most potent inhibitor of cholesterol biosynthesis, BAYw6228, at doses of 50, 100, 200 and 300 ug/day in patients with primary hypercholesterolemia. As a control group one out of six patients will receive lovastatin (40 mg/day) and one out of six patients will receive placebo. Up to 30 patients will be involved in the study which will last for a total of 34 weeks.